The beginning rise in obesity prevalence rates in South Africa was first noticed already in the early 1990s. Since then, several articles have discussed how the nutrition transition has affected people's body weights in the country. This article is the first one that uses longitudinal data from South Africa to reveal the short- and long-term effects that socio-economic and cultural factors have on the probability of becoming obese. The concept of 'benign' obesity seems to influence people's perceptions of an ideal body shape and thus model the preference for a higher body weight. Women are more affected by increasing body weights than men. We find that time invariant characteristics and long-term effects have the largest influence on the probability of becoming obese. To address the problems of obesity, we suggest implementing programs that change people's attitudes and behavior regarding food intake and physical activity. If people change their perception of what kind of body weight can be considered as being healthy, then a combination of different health programs can be successful.